Aqueous chromophore and/or effect-producing coating material, and use of the same

ABSTRACT

A color and/or effect coating material which is free from rheological aids based on phyllosilicates and comprises
     (A) a water-soluble, water-dilutable and/or water-dispersible polyurethane;   (B) a color and/or effect pigment;   (C) a dispersing assistant selected from the group consisting of the reaction products of
       (c1) a functionalized copolymer containing   (c11) a copolymerized olefinically unsaturated monomer isocyanate groups, anhydride groups and epoxy groups; and   (c12) a copolymerized olefinically unsaturated monomer which is free from isocyanate-, anhydride- and epoxy-reactive functional groups;   (c2) at least one homopolymeric polyalkylene glycol, and   (c3) at least one compound of the general formula I:
 
NR 2 —C(O)—NR 2   (I)
           in which the variables R are selected from the group consisting of hydrogen atoms and organic radicals, at least one of the radicals R containing at least one reactive functional group selected from the group consisting of isocyanate-, anhydride- and epoxy-reactive groups; and   
           
       (D) a rheological aid based on (meth)acrylate copolymers;
 
and its use to produce single-coat and multicoat color and/or effect paint systems.

RELATED APPLICATIONS

This application is based on PCT/EP2003/012310 filed on 5 Nov. 2003,which claims priority to DE 102 57 377.8, filed 9 Dec. 2002.

The present invention relates to a novel polyurethane-based aqueouscolor and/or effect coating material and to its use to producesingle-coat and multicoat color and/or effect coating systems inautomotive finishing, industrial coating, including coil coating andcontainer coating, plastics coating, the coating of interior andexterior architecture, furniture coating, and the coating of hollowglassware.

Aqueous color and/or effect coating materials, especially aqueousbasecoat materials, which comprise as binder a water-dispersible,ionically or nonionically stabilized polyurethane or a water-dispersible(meth)acrylate copolymer, at least one dispersing assistant for thecolor and/or effect pigments, selected from the group consisting of thereaction products of

-   (c1) at least one functionalized copolymer containing    -   (c11) at least one copolymerized olefinically unsaturated        monomer selected from the group consisting of olefinically        unsaturated monomers containing at least one reactive functional        group selected from the group consisting of isocyanate groups,        anhydride groups and epoxy groups; and    -   (c12) at least one copolymerized olefinically unsaturated        monomer which is free from isocyanate-, anhydride- and        epoxy-reactive functional groups;-   (c2) at least one homopolymeric polyalkylene glycol, and-   (c3) at least one compound of the general formula I:    NR₂—C(O)—NR₂  (I)    in which the variables R are selected from the group consisting of    hydrogen atoms and saturated and unsaturated, substituted and    unsubstituted, aliphatic, cycloaliphatic, aliphatic-cycloaliphatic,    aromatic, aliphatic-aromatic and cycloaliphatic-aromatic radicals    which may contain at least one amino group —NH—, at least one oxygen    atom —O— and/or at least one sulfur atom —S— and/or may be    cyclically linked to one another, at least one of the radicals R    containing at least one reactive functional group selected from the    group consisting of isocyanate-, anhydride- and epoxy-reactive    groups; and phyllosilicates, especially montmorillonites, as    rheology control additives, and also the color and/or effect paint    systems produced from them, are known from European patent    application EP 0 589 340 A1.

Aqueous color and/or effect coating materials, especially aqueousbasecoat materials, which comprise a water-dispersible (meth)acrylatecopolymer binder and a nonassociative Theological aid based on(meth)acrylate copolymers based on (C₁-C₆)-alkyl (meth)acrylate and(meth)acrylic acid, and also the color and/or effect paint systemsproduced from them, are known from German patent applications DE 197 41554 A1 and DE 196 52 842 A1.

These known aqueous color and/or effect coating materials and thesingle-coat or multicoat color and/or effect paint systems producedtherewith exhibit per se performance properties which are very good.

The known coating materials, however, require further improvement interms of their shear stability on stirring and in their settlingbehavior on storage at room temperature and on oven storage at 40° C.,so that the user, especially the automaker, no longer experiences anyproblems, such as loss of pseudoplasticity or phase separation, on theline.

Furthermore, it is necessary to improve further the adhesion propertiesof the known coatings, particularly of the paint systems, so that thereis no delamination and/or blushing, particularly following exposure tocondensation. These problems may occur both with the known originalfinishes and with the known refinishes.

It is an object of the present invention to provide novel aqueous colorand/or effect coating materials which are highly suitable as aqueousbasecoat material or as solid-color topcoat material for producingsingle-coat and multicoat color and/or effect paint systems. The novelaqueous color and/or effect coating materials ought to exceed the knowncoating materials in their storage stability, particularly their shearstability, and in their settling behavior. The novel single-coat ormulticoat color and/or effect paint systems ought to exceed the knownpaint systems in terms of their adhesion properties, particularlyfollowing exposure to condensation, and this should be the case bothwith the original finishes and with the refinishes.

The invention accordingly provides the novel aqueous color and/or effectcoating material which is free from rheological aids based onphyllosilicates and comprises

-   (A) at least one water-soluble, water-dilutable and/or    water-dispersible polyurethane selected from the group consisting of    polyurethanes which are grafted with olefinically unsaturated    compounds, are ionically or ionically and nonionically stabilized    and are based on polyisocyanates selected from the group consisting    of aliphatic, cycloaliphatic, aliphatic-cycloaliphatic, aromatic,    aliphatic-aromatic and cycloaliphatic-aromatic polyisocyanates;-   (B) at least one color and/or effect pigment;-   (C) at least one dispersing assistant for the color and/or effect    pigments, selected from the group consisting of the reaction    products of-   (c1) at least one functionalized copolymer containing    -   (c11) at least one copolymerized olefinically unsaturated        monomer selected from the group consisting of olefinically        unsaturated monomers containing at least one reactive functional        group selected from the group consisting of isocyanate groups,        anhydride groups and epoxy groups; and    -   (c12) at least one copolymerized olefinically unsaturated        monomer which is free from isocyanate-, anhydride- and        epoxy-reactive functional groups;-   (c2) at least one homopolymeric polyalkylene glycol, and-   (c3) at least one compound of the general formula I:    NR₂—C(O)—NR₂  (I)    -   in which the variables R are selected from the group consisting        of hydrogen atoms and saturated and unsaturated, substituted and        unsubstituted, aliphatic, cycloaliphatic,        aliphatic-cycloaliphatic, aromatic, aliphatic-aromatic and        cycloaliphatic-aromatic radicals which may contain at least one        amino group —NH—, at least one oxygen atom —O— and/or at least        one sulfur atom —S— and/or may be cyclically linked to one        another, at least one organic radical R being present and the        radical R or at least one of the radicals R containing at least        one reactive functional group selected from the group consisting        of isocyanate-, anhydride- and epoxy-reactive groups; and-   (D) at least one rheological aid based on (meth)acrylate copolymers.

The novel aqueous color and/or effect coating material free fromrheological aids based on phyllosilicates is referred to below as“coating material of the invention”.

Further subject matter of the invention will emerge from the descriptionwhich follows.

In the light of the prior art it was surprising and unforeseeable forthe skilled worker that the object on which the present invention wasbased could be achieved by means of the coating material of theinvention.

A further surprise was that it was possible to do without phyllosilicaterheological aids and to use only organic Theological aids. Thisresulted, surprisingly, after just a short time of shearing in acomparatively weak shear field, in a coating material of the inventionwhich had the necessary pseudoplasticity.

A further surprise was that the coating material of the invention had abetter stability on storage, both on room temperature storage and on 40°C. oven storage, than the known coating materials. Not least, the shearstability had also been improved. Phase separation was no longerobserved in the case of the coating material of the invention.

A particular surprise, however, was that the coatings of the inventionproduced from the coating material of the invention, especially thebasecoats and solid-color topcoats, were free from wetting defects,runs, popping marks, pinholes, clouds, effect defects, water spots, andshifts in shade. They also met all of the requirements posed in terms ofwet adhesion and stonechip resistance following exposure to constantcondensation conditions and following exposure to boiling water andsubsequent jetting with a high pressure steam jet, and exceeded theknown coatings in this respect.

The coating material of the invention is curable thermally or boththermally and with actinic radiation. It may be thermallyself-crosslinking or externally crosslinking.

In the context of the present invention, actinic radiation iselectromagnetic radiation, such as near infrared (NIR), visible light,UV radiation or X-rays, especially UV radiation, and corpuscularradiation such as electron beams.

In the context of the present invention, the term “self-crosslinking”denotes the property of a binder to undergo crosslinking reactions withitself. A precondition for this is that the binder already contains bothtypes of complementary reactive functional groups necessary forcrosslinking, or reactive functional groups which react “withthemselves”. “Externally crosslinking”, on the other hand, is used todenote those coating materials in which one type of the complementaryreactive functional groups is present in the binder and the other typein a curing or crosslinking agent. For further details, reference ismade to Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag,Stuttgart, N.Y., 1998, “Curing”, pages 274 to 276, especially page 275,bottom.

If the coating material of the invention is curable thermally and withactinic radiation, this is also referred to by those in the art as “dualcure”.

The coating material of the invention is aqueous. This means that itsconstituents are present in solution and/or dispersion in water or in anaqueous medium consisting of water and minor amounts of at least onewater-miscible organic solvent. “Minor amounts” here are those which donot destroy the aqueous nature of the medium.

The coating material of the invention is a one-component system.

In the context of the present invention, a one-component system is aphysically curing coating material or a coating material which curesthermally, or thermally and with actinic radiation, in which the binderand the crosslinking agent are present alongside one another, i.e., inone component. The prerequisite for this is that the two constituentscrosslink with one another only at relatively high temperatures and/oron exposure to actinic radiation.

The coating material of the invention is a two-component ormulticomponent system.

In the context of the present invention, two-component or multicomponentsystems are coating materials whose crosslinking agent, because of itshigh reactivity, must be stored separately from other constituents ofthe coating materials prior to application.

Examples of suitable complementary reactive functional groups for use inaccordance with the invention are compiled in the following overview. Insaid overview, the variable R¹ is an acyclic or cyclic aliphatic, anaromatic, and/or an aromatic-aliphatic (araliphatic) radical; thevariables R² and R³ are identical or different aliphatic radicals or arelinked with one another to form an aliphatic or heteroaliphatic ring.

Overview: Examples of Complementary Functional Groups

binder and crosslinking agent or crosslinking agent and binder —SH—C(O)—OH —NH₂ —C(O)—O—C(O)— —OH —NCO —NH—C(O)—OR¹ —CH₂—OH —CH₂—O—R¹—NH—CH₂—O—R¹ —NH—CH₂—OH —N(—CH₂—O—R¹)₂ —NH—C(O)—CH(—C(O)OR¹)₂—NH—C(O)—CH(—C(O)OR)(—C(O)—R¹) —NH—C(O)—NR²R³ >Si(OR¹)₂

—C(O)—OH

—N═C═N— —C(O)—N(CH₂—CH₂—OH)₂

The selection of the respective complementary reactive functional groupsis guided firstly by the consideration that during the preparation,storage, and application of the coating materials of the invention theymust not undergo any unwanted reactions, especially no prematurecrosslinking, and/or, if appropriate, must not disrupt or inhibit curingwith actinic radiation, and secondly by the temperature range withinwhich crosslinking is to take place.

In the case of the one-component systems of the invention, crosslinkingtemperatures of from 100 to 180° C. are preferably employed. Preferenceis therefore given to the use of binders (A) containing thio, hydroxyl,N-methylolamino, N-alkoxymethylamino and/or carboxyl groups, preferablyhydroxyl groups, on the one hand and of crosslinking agents containinganhydride, carboxyl, epoxy, blocked isocyanate, methylol, methylolether, siloxane, carbonate, amino, hydroxyl and/orbeta-hydroxyalkylamide groups, preferably blocked isocyanate, oralkoxymethylamino groups, on the other.

In the case of self-crosslinking coating materials of the invention, thebinders (A) contain, in particular, methylol, methylol ether and/orN-alkoxymethylamino groups.

In the case of the two-component or multicomponent systems of theinvention it is preferred to employ crosslinking temperatures below 100°C. Complementary reactive functional groups used are preferably thiol,hydroxyl or primary and secondary amino groups, especially hydroxylgroups, on the one hand and isocyanate groups on the other.

The first essential constituent of the coating material of the inventionis the polyurethane (A), which acts as binder. In accordance with theinvention, it is selected from the group consisting of polyurethaneswhich are grafted with olefinically unsaturated compounds, are ionicallyand nonionically stabilized and are based on polyisocyanates selectedfrom the group consisting of aliphatic, cycloaliphatic,aliphatic-cycloaliphatic, aromatic, aliphatic-aromatic andcycloaliphatic-aromatic polyisocyanates.

The polyurethane (A) is of linear, branched, or comb construction.

Viewed in terms of method, the preparation of the polyurethanes (A) foruse in accordance with the invention has no special features but insteadtakes place, for example, as described in patents EP 0 089 497 A1, DE197 22 862 C2, DE 196 45 761 A1, DE 43 39 870 A1, DE 197 36 535 A1, andDE 44 37 535 A1, EP 0 522 419 A1, and EP 0 522 420 A1.

In a first preferred variant of the preparation of polyurethanes (A),

-   (a1) at least one polyisocyanate, especially a diisocyanate, and    also, if desired, a monoisocyanate are reacted with-   (a2) at least one polyol, especially a diol,-   (a3) at least one compound having at least one anionic group and/or    at least one functional group convertible to an anionic group, and    at least one isocyanate-reactive functional group, or alternatively-   (a4) at least one compound having at least one cationic group and/or    at least one functional group convertible to a cationic group, and    at least one isocyanate-reactive functional group, and also, if    desired,-   (a5) at least one chain extender.

In a further preferred variant of the preparation process,

-   (a6) at least one compound having at least one nonionic, hydrophilic    group and at least one isocyanate-reactive functional group is used    additionally to the compounds (a3) or (a4).

In yet a further preferred variant of the preparation process,

-   (a7) at least one compound having at least one olefinically    unsaturated group and at least one isocyanate-reactive functional    group, or alternatively-   (a8) at least one compound having at least one olefinically    unsaturated group and at least one isocyanate group,    is additionally incorporated.

The polyurethanes (A) prepared from the above-described compounds (a1)to (a8) are grafted with olefinically unsaturated monomers (a9), to givepolyurethane-(meth)acrylate graft copolymers (A).

Examples of suitable diisocyanates (a1) are isophorone diisocyanate(i.e., 5-isocyanato-1-isocyanatomethyl-1,3,3-trimethylcyclohexane),5-isocyanato-1-(2-isocyanatoeth-1-yl)-1,3,3-trimethylcyclohexane,5-isocyanato-1-(3-isocyanatoprop-1-yl)-1,3,3-trimethylcyclohexane,5-isocyanato-(4-isocyanatobut-1-yl)-1,3,3-trimethylcyclohexane,1-isocyanato-2-(3-isocyanatoprop-1-yl)cyclohexane,1-isocyanato-2-(3-isocyanatoeth-1-yl)cyclohexane,1-isocyanato-2-(4-isocyanatobut-1-yl)cyclohexane,1,2-diisocyanatocyclobutane, 1,3-diisocyanatocyclobutane,1,2-diisocyanatocyclopentane, 1,3-diisocyanatocyclopentane,1,2-diisocyanatocyclohexane, 1,3-diisocyanatocyclohexane,1,4-diisocyanatocyclohexane, dicyclohexylmethane-2,4′-diisocyanate,trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylenediisocyanate, hexamethylene diisocyanate, ethyl ethylene diisocyanate,trimethylhexane diisocyanate, heptamethylene diisocyanate ordiisocyanates derived from dimeric fatty acids, as marketed under thecommercial designation DDI 1410 by Henkel and described in patents WO97/49745 and WO 97/49747, especially2-heptyl-3,4-bis(9-isocyanatononyl)-1-pentylcyclohexane, or 1,2-, 1,4-or 1,3-bis(isocyanatomethyl)cyclohexane, 1,2-, 1,4- or1,3-bis(2-isocyanatoeth-1-yl)cyclohexane,1,3-bis(3-isocyanatoprop-1-yl)cyclohexane, 1,2-, 1,4- or1,3-bis(4-isocyanatobut-1-yl)cyclohexane, liquidbis(4-isocyanatocyclohexyl)methane with a trans/trans content of up to30% by weight, preferably 25% by weight, and in particular 20% byweight, as described in patents DE 44 14 032 A1, GB 1220717 A, DE 16 18795 A1, and DE 17 93 785 A1; tetramethylxylylidene diisocyanate (TMXDI®from CYTEC), tolylene diisocyanate, xylylene diisocyanate, bisphenylenediisocyanate, naphthylene diisocyanate or diphenylmethane diisocyanate.

Examples of suitable polyisocyanates (a1) based on the above-describeddiisocyanates (a1) are isocyanato-containing polyurethane prepolymersprepared by reacting polyols with an excess of at least one of theabove-described diisocyanates, and/or polyisocyanates containingisocyanurate, biuret, allophanate, iminooxadiazinedione, urethane, ureaand/or uretdione groups, such as are formed by catalytic oligomerizationof diisocyanates using suitable catalysts. Examples of suitablepolyisocyanates (A) of this kind and processes for preparing them areknown, for example, from the patents and patent applications CA2,163,591 A1, U.S. Pat. Nos. 4,419,513 A, 4,454,317 A, EP 0 646 608 A1,U.S. Pat. No. 4,801,675 A, EP 0 183 976 A1, DE 40 15 155 A1, EP 0 303150 A1, EP 0 496 208 A1, EP 0 524 500 A1, EP 0 566 037 A1, U.S. Pat.Nos. 5,258,482 A, 5,290,902 A, EP 0 649 806 A1, DE 42 29 183 A1 and EP 0531 820 A1.

It is preferred to use polyisocyanates containing on average from 2.5 to5 isocyanate groups per molecule and having viscosities of from 100 to10,000, preferably from 100 to 5000 mPas. Furthermore, thepolyisocyanates may have been modified hydrophilically orhydrophobically in a customary and known manner.

Very particular preference is given to the use of mixtures ofpolyisocyanates (a1) based on the above-described diisocyanates (a1) andcontaining uretdione and/or isocyanurate and/or allophanate groups.

Examples of suitable monoisocyanates (a1) are phenyl isocyanate,cyclohexyl isocyanate, stearyl isocyanate, vinyl isocyanate,methacryloyl isocyanate, and/or1-(1-isocyanato-1-methylethyl)-3-(1-methylethenyl)benzene (TMI® fromCYTEC).

Examples of suitable polyols (a2) are saturated or olefinicallyunsaturated polyester polyols prepared by reacting

-   -   unsulfonated or sulfonated saturated and/or unsaturated        polycarboxylic acids or their esterifiable derivatives, together        if desired with monocarboxylic acids, and    -   saturated and/or unsaturated polyols, together if desired with        monools.

Examples of suitable polycarboxylic acids are aromatic, aliphatic, andcycloaliphatic polycarboxylic acids. It is preferred to use aromaticand/or aliphatic polycarboxylic acids.

Examples of suitable aromatic polycarboxylic acids are phthalic acid,isophthalic acid, terephthalic acid, phthalic, isophthalic orterephthalic monosulfonate, or halophthalic acids, such as tetrachloro-and tetrabromophthalic acid, among which isophthalic acid isadvantageous and is therefore used with preference.

Examples of suitable acyclic aliphatic or unsaturated polycarboxylicacids are oxalic acid, malonic acid, succinic acid, glutaric acid,adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid,undecanedicarboxylic acid, dodecanedicarboxylic acid, or dimeric fattyacids, or maleic acid, fumaric acid or itaconic acid, among which adipicacid, glutaric acid, azelaic acid, sebacic acid, dimeric fatty acids,and maleic acid are advantageous and are therefore used with preference.

Examples of suitable cycloaliphatic and cyclic unsaturatedpolycarboxylic acids are 1,2-cyclobutanedicarboxylic acid,1,3-cyclobutanedicarboxylic acid, 1,2-cyclopentanedicarboxylic acid,1,3-cyclopentanedicarboxylic acid, hexahydrophthalic acid,1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid,4-methylhexahydrophthalic acid, tricyclodecanedicarboxylic acid,tetrahydrophthalic acid, and 4-methyltetrahydrophthalic acid. Thesedicarboxylic acids may be used both in their cis and in their transform, and also as a mixture of both forms.

Also suitable are the esterifiable derivatives of the abovementionedpolycarboxylic acids, such as their monoesters or polyesters withaliphatic alcohols having 1 to 4 carbon atoms or hydroxy alcohols having1 to 4 carbon atoms, for example. Furthermore, it is also possible touse the anhydrides of the abovementioned polycarboxylic acids, wherethey exist.

If desired, together with the polycarboxylic acids, it is also possibleto use monocarboxylic acids, such as benzoic acid, tert-butylbenzoicacid, lauric acid, isononanoic acid, fatty acids of naturally occurringoils, acrylic acid, methacrylic acid, ethacrylic acid, and crotonicacid, for example. A preferred monocarboxylic acid used is isononanoicacid.

Examples of suitable polyols are diols and triols, especially diols.Usually, triols are used in addition to the diols in minor amounts inorder to introduce branching sites into the polyester polyols (a2).

Suitable diols are ethylene glycol, 1,2- or 1,3-propanediol, 1,2-, 1,3-or 1,4-butanediol, 1,2-, 1,3-, 1,4- or 1,5-pentanediol, 1,2-, 1,3-,1,4-, 1,5- or 1,6-hexanediol, neopentyl hydroxypivalate, neopentylglycol, diethylene glycol, 1,2-, 1,3- or 1,4-cyclohexanediol, 1,2-, 1,3-or 1,4-cyclohexanedimethanol, trimethylpentanediol,ethylbutylpropanediol, the positionally isomeric diethyloctanediols,2-butyl-2-ethyl-1,3-propanediol, 2-butyl-2-methyl-1,3-propanediol,2-phenyl-2-methyl-1,3-propanediol, 2-propyl-2-ethyl-1,3-propanediol,2-di-tert-butyl-1,3-propanediol, 2-butyl-2-propyl-1,3-propanediol,1-dihydroxymethylbicyclo [2.2.1]heptane, 2,2-diethyl-1,3-propanediol,2,2-dipropyl-1,3-propanediol, 2-cyclohexyl-2-methyl-1,3-propanediol,2,5-dimethyl-2,5-hexanediol, 2,5-diethyl-2,5-hexanediol,2-ethyl-5-methyl-2,5-hexanediol, 2,4-dimethyl-2,4-pentanediol,2,3-dimethyl-2,3-butanediol, 1,4-bis(2′-hydroxypropyl)benzene, and1,3-bis(2′-hydroxypropyl)benzene. These diols may also be used per se(diols a2) to prepare the polyurethanes (A).

Of these diols, hexanediol and neopentyl glycol are particularlyadvantageous and are therefore used with particular preference.

Examples of suitable triols are trimethylolethane, trimethylolpropane,and glycerol, especially trimethylolpropane.

The abovementioned triols may also be used per se (triols a2; cf. patentEP 0 339 433 A1) to prepare the polyurethanes.

If desired, minor amounts of monools may also be used. Examples ofsuitable monools are alcohols or phenols such as ethanol, propanol,n-butanol, sec-butanol, tert-butanol, amyl alcohols, hexanols, fattyalcohols, allyl alcohol, or phenol.

The preparation of the polyester polyols (a2) may be conducted in thepresence of small amounts of an appropriate solvent as entrainer.Examples of entrainers used are aromatic hydrocarbons, such as, inparticular, xylene and (cyclo)aliphatic hydrocarbons, e.g., cyclohexaneor methylcyclohexane.

Further examples of suitable polyols (a2) are polyester diols which areobtained by reacting a lactone with a diol. They are notable for thepresence of terminal hydroxyl groups and repeating polyester units ofthe formula —(—CO—(CHR⁴)_(m)—CH₂—O—)—. Here, the index m is preferablyfrom 4 to 6 and the substituent R⁴ is hydrogen or an alkyl, cycloalkyl,or alkoxy radical. No one substituent contains more than 12 carbonatoms. The total number of carbon atoms in the substituent does notexceed 12 per lactone ring. Examples are hydroxycaproic acid,hydroxybutyric acid, hydroxydecanoic acid, and/or hydroxystearic acid.

Preferred for preparing the polyester diols (a2) is the unsubstitutedε-caprolactone, where m is 4 and all substituents R⁴ are hydrogen. Thereaction with lactone is started by low molecular mass polyols such asethylene glycol, 1,3-propanediol, 1,4-butanediol, ordimethylolcyclohexane. It is also possible to react other reactioncomponents, such as ethylenediamine, alkyldialkanolamines, or else urea,with caprolactone. Further suitable diols of relatively high molecularmass include polylactam diols, which are prepared by reacting, say,ε-caprolactam with low molecular mass diols.

Further examples of suitable polyols (a2) are polyether polyols,especially those having a number-average molecular weight of from 400 to5000, in particular from 400 to 3000. Examples of particularly suitablepolyether diols are those of the general formulaH—(—O—(CHR⁵)_(o)—)_(p)OH, in which the substituent R⁵ is hydrogen or alower, unsubstituted or substituted alkyl radical, the index o is from 2to 6, preferably from 3 to 4, and the index p is from 2 to 100,preferably from 5 to 50. Especially suitable examples are linear orbranched polyether diols such as poly(oxyethylene) glycols,poly(oxypropylene) glycols, and poly(oxybutylene) glycols.

On the one hand, the polyether diols (a2) should not introduce excessiveamounts of ether groups, since otherwise the coatings produced using thepolyurethane-(meth)acrylate graft copolymers (A) are swollen by water.On the other hand, they may be used in amounts which contribute tostabilizing (compounds a6) the dispersions of the polyurethanes (A).

Examples of suitable functional groups for use in accordance with theinvention which may be converted into anions by neutralizing agents arecarboxylic acid, sulfonic acid, and phosphonic acid groups, especiallycarboxylic acid groups.

Examples of suitable anionic groups for use in accordance with theinvention are carboxylate, sulfonate, and phosphonate groups, especiallycarboxylate groups.

Examples of suitable neutralizing agents for functional groupsconvertible into anions are ammonia, ammonium salts, such as ammoniumcarbonate or ammonium hydrogen carbonate, for example, and amines, suchas trimethylamine, triethylamine, tributylamine, dimethylaniline,diethylaniline, triphenylamine, dimethylethanolamine,diethylethanolamine, methyldiethanolamine, triethanolamine, and thelike, for example. Neutralization may take place in organic or aqueousphase. Preference is given to the use of dimethylethanolamine as aneutralizing agent.

(Potentially) anionic groups are introduced into the polyurethanemolecules by way of the incorporation of compounds (a3) which contain inthe molecule at least one isocyanate-reactive group and at least one,especially one, group capable of forming anions; the amount to be usedmay be calculated from the target acid number.

Suitable isocyanate-reactive functional groups are, in particular,hydroxyl groups, thiol groups, and primary and/or secondary aminogroups, of which the hydroxyl groups are used with preference.

Very suitable compounds (a3) are those containing two groups in themolecule which are reactive toward isocyanate groups. Accordingly it ispossible to use, for example, alkanoic acids having two substituents onthe α carbon atom. The substituent may be a hydroxyl group, an alkylgroup, or, preferably, an alkylol group. These alkanoic acids have atleast one, generally from 1 to 3, carboxyl group(s) in the molecule.They have 2 to about 25, preferably 3 to 10, carbon atoms. Examples ofsuitable alkanoic acids are dihydroxypropionic acid, dihydroxysuccinicacid, and dihydroxybenzoic acid. A particularly preferred group ofalkanoic acids comprises the α,α-dimethylolalkanoic acids of the generalformula R⁶—C(CH₂OH)₂COOH, where R⁶ is a hydrogen atom or an alkyl grouphaving up to about 20 carbon atoms. Examples of especially suitablealkanoic acids are 2,2-dimethylolacetic acid, 2,2-dimethylolpropionicacid, 2,2-dimethylolbutyric acid, and 2,2-dimethylolpentanoic acid. Thepreferred dihydroxyalkanoic acid is 2,2-dimethylolpropionic acid.Examples of compounds containing amino groups are α,ω-diaminovalericacid, 3,4-diaminobenzoic acid, 2,4-diaminotoluenesulfonic acid, and2,4-diaminodiphenyl ether sulfonic acid.

Examples of suitable functional groups for use in accordance with theinvention that may be converted into cations by neutralizing agentsand/or quaternizing agents are primary, secondary or tertiary aminogroups, secondary sulfide groups or tertiary phosphine groups,especially tertiary amino groups or secondary sulfide groups.

Examples of suitable cationic groups for use in accordance with theinvention are primary, secondary, tertiary or quaternary ammoniumgroups, tertiary sulfonium groups or quaternary phosphonium groups,preferably quaternary ammonium groups or tertiary sulfonium groups, butespecially tertiary ammonium groups.

Examples of suitable neutralizing agents for functional groupsconvertible into cations are organic and inorganic acids such assulfuric acid, hydrochloric acid, phosphoric acid, formic acid, aceticacid, lactic acid, dimethylolpropionic acid, and citric acid.

(Potentially) cationic groups are introduced into the polyurethanes (A)via the incorporation of compounds (a4) which contain at least one,especially two, isocyanate-reactive groups and at least one groupcapable of forming cations in the molecule; the amount to be used may becalculated from the target amine number.

Suitable isocyanate-reactive functional groups are those describedabove.

Examples of suitable compounds (a4) are 2,2-dimethylolethyl- or-propylamine blocked with a ketone, the resulting ketoxime group beinghydrolyzed again prior to the formation of the cationic group, orN,N-dimethyl-, N,N-diethyl- or N-methyl-N-ethyl-2,2-dimethylolethyl- or-propylamine.

The total amount of neutralizing agent used in the coating material ofthe invention is chosen so that from 1 to 100 equivalents, preferablyfrom 50 to 90 equivalents, of the potentially anionic or cationicfunctional groups of the polyurethane (A) are neutralized.

Polyols, polyamines and amino alcohols (a5) may be used for chainextension.

Suitable polyols (a5) for the chain extension are polyols having up to36 carbon atoms per molecule, such as ethylene glycol, diethyleneglycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol,1,4-butanediol, 1,2-butylene glycol, 1,6-hexanediol, trimethylolpropane,castor oil or hydrogenated castor oil, ditrimethylolpropane ether,pentaerythritol, 1,2-cyclohexanediol, 1,4-cyclohexanedimethanol,bisphenol A, bisphenol F, neopentyl glycol, neopentyl glycolhydroxypivalate, hydroxyethylated or hydroxypropylated bisphenol A,hydrogenated bisphenol A, or mixtures thereof (cf. patents EP 0 339 433A1, EP 0 436 941 A1 or EP0 517 707 A1).

Examples of suitable polyamines (a5) have at least two primary and/orsecondary amino groups. Polyamines (a5) are essentiallyalkylenepolyamines having 1 to 40 carbon atoms, preferably about 2 to 15carbon atoms. They may carry substituents which have no hydrogen atomsthat are reactive with isocyanate groups. Examples are polyamines (a5)having a linear or branched aliphatic, cycloaliphatic or aromaticstructure and at least two primary amino groups.

Appropriate diamines (a5) are hydrazine, ethylenediamine,propylenediamine, 1,4-butylenediamine, piperazine,1,4-cyclohexyldimethylamine, 1,6-hexamethylenediamine,trimethylhexamethylenediamine, menthanediamine, isophoronediamine,4,4′-diaminodicyclohexylmethane, and aminoethylethanolamine. Preferreddiamines (a5) are hydrazine, alkyl- or cycloalkyldiamines such aspropylenediamine and 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane.

It is also possible to use polyamines (a5), which contain more than twoamino groups in the molecule. In these cases, however, it should beensured—by using monoamines (a5) as well, for example—that crosslinkedpolyurethane resins (A) are not obtained. Polyamines (a5) of this kindwhich may be used are diethylenetriamine, triethylenetetramine,dipropylenediamine, and dibutylenetriamine. An example of a monoamine isethylhexylamine (cf. patent EP-A-0 089 497).

Examples of suitable amino alcohols (a5) are ethanolamine anddiethanolamine.

Examples of suitable compounds (a6) by means of which hydrophilicnonionic functional groups are introduced into the polyurethanes (A) arethe above-described polyether diols or alkoxypoly(oxyalkylene) alcoholswith the general formula R⁷O—(—CH₂—CHR⁸—O—)_(r)H in which R⁷ is an alkylradical having 1 to 6 carbon atoms, R⁸ is a hydrogen atom or an alkylradical having 1 to 6 carbon atoms, and the index r is a number between20 and 75 (cf. patents EP 0 354 261 A1 and EP0 424 705 A1).

The polyurethanes (A) may contain terminal and/or lateral olefinicallyunsaturated groups. Groups of this kind are introduced with the aid ofcompounds (a7) having at least one, especially two, isocyanate-reactivegroup(s), especially hydroxyl groups, and at least one, especially one,olefinically unsaturated group. However, it is also possible to usecompounds (a8) containing at least one isocyanate group and at leastone, especially one, olefinically unsaturated group. Preference is givento the compounds (a7).

Suitable olefinically unsaturated groups are basically all groups whichcontain at least one, especially one, double bond. In the context of thepresent invention, a double bond is a carbon-carbon double bond.Examples of highly suitable olefinically unsaturated groups are(meth)acrylate, ethacrylate, crotonate, cinnamate, vinyl ether, vinylester, vinyl, dicyclopentadienyl, norbornenyl, isoprenyl, isopropenyl,allyl and/or butenyl groups; dicyclopentadienyl ether, norbornenylether, isoprenyl ether, isopropenyl ether, allyl ether or butenyl ethergroups; and/or dicyclopentadienyl ester, norbornenyl ester, isoprenylester, isopropenyl ester, allyl ester and/or butenyl ester groups.

Examples of suitable compounds (a7) and (a8) are trimethylolpropanemonoallyl ether or trimethylolpropane mono(meth)acrylate (a7) or1-(1-isocyanato-1-methylethyl)-3-(1-methylethenyl)benzene (i.e.,dimethyl-m-isopropenylbenzyl isocyanate) (a8), especiallytrimethylolpropane monoallyl ether (a7).

The above-described compounds (a7) and (a8) are preferably used inamounts such as to give polyurethanes (A) having on average at least0.5, preferably at least 1, and in particular at least 1.5, olefinicallyunsaturated double bond(s) in the molecule.

The polyurethanes (A) may be grafted with olefinically unsaturatedmonomers (a9). Examples of suitable monomers (a9) are the following:

Monomers (a91):

Hydroxyalkyl esters of acrylic acid, methacrylic acid or anotheralpha,beta-ethylenically unsaturated carboxylic acid, which derive froman alkylene glycol which is esterified with the acid, or are obtainableby reacting the acid with an alkylene oxide, especially hydroxyalkylesters of acrylic acid, methacrylic acid or ethacrylic acid in which thehydroxyalkyl group contains up to 20 carbon atoms, such as2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 3-hydroxybutyl,4-hydroxybutyl acrylate, methacrylate, ethacrylate or crotonate;1,4-bis(hydroxymethyl)cyclohexane,octahydro-4,7-methano-1H-indenedimethanol or methylpropanediolmonoacrylate, monomethacrylate, monoethacrylate or monocrotonate; orreaction products of cyclic esters, such as ε-caprolactone, for example,and these hydroxyalkyl esters; or olefinically unsaturated alcohols suchas allyl alcohol or ethers of polyols such as trimethylolpropane diallylether or pentaerythritol diallyl or triallyl ether. These monomers (a91)of higher functionality are generally used only in minor amounts. In thecontext of the present invention, minor amounts of higher-functionalmonomers here are those amounts which do not lead to crosslinking orgelling of the polyacrylate resins. For example, the fraction oftrimethylolpropane diallyl ether may be from 2 to 10% by weight, basedon the overall weight of the monomers (a91) to (a96) used to prepare thepolyacrylate resin.

Monomers (a92):

(Meth)acrylic alkyl or cycloalkyl esters having up to 20 carbon atoms inthe alkyl radical, especially methyl, ethyl, propyl, n-butyl, sec-butyl,tert-butyl, hexyl, ethylhexyl, stearyl and lauryl acrylate ormethacrylate; cycloaliphatic (meth)acrylic esters, especiallycyclohexyl, isobornyl, dicyclopentadienyl,octahydro-4,7-methano-1H-indenemethanol or tert-butylcyclohexyl(meth)acrylate; (meth)acrylic oxaalkyl esters or oxacycloalkyl esterssuch as ethyltriglycol (meth)acrylate and methoxyoligoglycol(meth)acrylate having a molecular weight Mn of preferably 550; or otherethoxylated and/or propoxylated, hydroxyl-free (meth)acrylic acidderivatives. These may include, in minor amounts, higher-functional(meth)acrylic alkyl or cycloalkyl esters such as ethylene glycol,propylene glycol, diethylene glycol, dipropylene glycol, butyleneglycol, 1,5-pentanediol, 1,6-hexanediol,octahydro-4,7-methano-1H-indenedimethanol or cyclohexane-1,2-, -1,3- or-1,4-diol di(meth)acrylate; trimethylolpropane di- or tri(meth)acrylate;or pentaerythritol di-, tri- or tetra(meth)acrylate. In the context ofthe present invention, minor amounts of higher-functional monomers (a92)here are those which do not lead to crosslinking or gelling of thepolyacrylate resins.

Monomers (a93):

Ethylenically unsaturated monomers which carry at least one acid group,preferably a carboxyl group, per molecule, or a mixture of suchmonomers. Monomers (a93) used for particular preference are acrylic acidand/or methacrylic acid. However, it is also possible to use otherethylenically unsaturated carboxylic acids having up to 6 carbon atomsin the molecule. Examples of such acids are ethacrylic acid, crotonicacid, maleic acid, fumaric acid, and itaconic acid. It is also possibleto use ethylenically unsaturated sulfonic or phosphonic acids, and/ortheir partial esters, as component (a93). Further suitable monomers(a93) include mono(meth)acryloyloxyethyl maleate, succinate, andphthalate.

Monomers (a94):

Vinyl esters of alpha-branched monocarboxylic acids having 5 to 18carbon atoms in the molecule. The branched monocarboxylic acids may beobtained by reacting formic acid or carbon monoxide and water witholefins in the presence of a liquid, strongly acidic catalyst; theolefins may be cracking products of paraffinic hydrocarbons, such asmineral oil fractions, and may comprise both branched and straight-chainacyclic and/or cycloaliphatic olefins. The reaction of such olefins withformic acid and/or with carbon monoxide and water produces a mixture ofcarboxylic acids in which the carboxyl groups are located predominantlyon a quaternary carbon atom. Examples of other olefinic startingmaterials are propylene trimer, propylene tetramer, and diisobutylene.Alternatively, the vinyl esters may be prepared conventionally from theacids, for example, by reacting the acid with acetylene. Particularpreference is given—owing to their ready availability—to vinyl esters ofsaturated aliphatic monocarboxylic acids having 9 to 11 carbon atomsthat are branched on the alpha carbon atom.

Monomers (a95):

Reaction products of acrylic acid and/or methacrylic acid with theglycidyl ester of an alpha-branched monocarboxylic acid having 5 to 18carbon atoms per molecule. The reaction of the acrylic or methacrylicacid with the glycidyl ester of a carboxylic acid having a tertiaryalpha carbon atom may take place before, during or after thepolymerization reaction. As component (a95) it is preferred to use thereaction product of acrylic and/or methacrylic acid with the glycidylester of Versatic® acid. This glycidyl ester is available commerciallyunder the name Cardura® E10. For further details, refer to Römpp LexikonLacke und Druckfarben, Georg Thieme Verlag, Stuttgart, New York*/, 1998,pages 605 and 606.

Monomers (a96):

Ethylenically unsaturated monomers which are essentially free from acidgroups, such as

-   -   olefins such as ethylene, propylene, 1-butene, 1-pentene,        1-hexene, cyclohexene, cyclopentene, norbornene, butadiene,        isoprene, cyclopentadiene and/or dicyclopentadiene;    -   (meth)acrylamides such as (meth)acrylamide, N-methyl-,        N,N-dimethyl-, N-ethyl, N,N-diethyl, N-propyl, N,N-dipropyl,        N-butyl, N,N-dibutyl, N-cyclohexyl- and/or N,N-cyclohexyl        methyl-(meth)acrylamide;    -   monomers containing epoxide groups such as the glycidyl ester of        acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid,        maleic acid, fumaric acid and/or itaconic acid;    -   vinylaromatic hydrocarbons, such as styrene,        alpha-alkylstyrenes, especially alpha-methylstyrene and/or        vinyltoluene;    -   diarylethylenes, especially those of the general formula II:        R⁹R¹⁰C═CR¹¹R¹²  (II),    -   in which the radicals R⁹, R¹⁰, R¹¹ and R¹² in each case        independently of one another are hydrogen atoms or substituted        or unsubstituted alkyl, cycloalkyl, alkylcycloalkyl,        cycloalkyalkyl, aryl, alkylaryl, cycloalkylaryl, arylalkyl or        arylcycloalkyl radicals, with the proviso that at least two of        the variables R⁹, R¹⁰, R¹¹ and R¹² are substituted or        unsubstituted aryl, arylalkyl or arylcycloalkyl radicals,        especially substituted or unsubstituted aryl radicals. Examples        of suitable alkyl radicals are methyl, ethyl, propyl, isopropyl,        n-butyl, isobutyl, tert-butyl, amyl, hexyl or 2-ethylhexyl.        Examples of suitable cycloalkyl radicals are cyclobutyl,        cyclopentyl or cyclohexyl. Examples of suitable alkylcycloalkyl        radicals are methylenecyclohexane, ethylenecyclohexane or        propane-1,3-diylcyclohexane. Examples of suitable        cycloalkylalkyl radicals are 2-, 3- or 4-methyl-, -ethyl-,        -propyl- or -butylcyclohex-1-yl. Examples of suitable aryl        radicals are phenyl, naphthyl or biphenylyl, preferably phenyl        and naphthyl, and especially phenyl. Examples of suitable        alkylaryl radicals are benzyl or ethylene- or        propane-1,3-diyl-benzene. Examples of suitable cycloalkylaryl        radicals are 2-, 3- or 4-phenylcyclohex-1-yl. Examples of        suitable arylalkyl radicals are 2-, 3- or 4-methyl-, -ethyl-,        -propyl- or -butylphen-1-yl. Examples of suitable arylcycloalkyl        radicals are 2-, 3- or 4-cyclohexylphen-1-yl. The aryl radicals        R⁹, R¹⁰, R¹¹ and/or R¹² are preferably phenyl or naphthyl        radicals, especially phenyl radicals. The substituents that may        be present in the radicals R⁹, R¹⁰, R¹¹ and/or R¹² are        electron-withdrawing or electron-donating atoms or organic        radicals, especially halogen atoms, nitrile, nitro, partially or        fully halogenated alkyl, cycloalkyl, alkylcycloalkyl,        cycloalkylalkyl, aryl, alkylaryl, cycloalkylaryl, arylalkyl and        arylcycloalkyl radicals; aryloxy, alkyloxy and cycloalkyloxy        radicals; arylthio, alkylthio and cycloalkylthio radicals,        and/or primary, secondary and/or tertiary amino groups.        Particularly advantageous are diphenylethylene,        dinaphthaleneethylene, cis- or trans-stilbene,        vinylidenebis(4-N,N-dimethylaminobenzene),        vinylidenebis(4-aminobenzene) or vinylidenebis(4-nitrobenzene),        especially diphenylethylene (DPE), and so are used with        preference. Preferably, these monomers (a96) are not used as the        sole monomers, but instead are always used together with other        monomers (a), in which case they advantageously regulate the        copolymerization such that a free-radical copolymerization in        batch mode is also possible;    -   nitriles such as acrylonitrile and/or methacrylonitrile;    -   vinyl compounds such as vinyl chloride, vinyl fluoride,        vinylidene dichloride, vinylidene difluoride;        N-vinylpyrrolidone; vinyl ethers such as ethyl vinyl ether,        n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl        ether, isobutyl vinyl ether and/or vinyl cyclohexyl ether; vinyl        esters such as vinyl acetate, vinyl propionate, vinyl butyrate,        vinyl pivalate, vinyl esters of Versatic® acids, which are        marketed under the brand name VeoVa® by the company Deutsche        Shell Chemie (for further details, refer to Römpp Lexikon Lacke        und Druckfarben, Georg Thieme Verlag, Stuttgart, New York, 1998,        page 598 and also pages 605 and 606), and/or the vinyl ester of        2-methyl-2-ethylheptanoic acid; and/or    -   polysiloxane macromonomers having a number-average molecular        weight Mn of from 1000 to 40,000, preferably from 2000 to        20,000, with particular preference from 2500 to 10,000, and in        particular from 3000 to 7000 and having on average from 0.5 to        2.5, preferably from 0.5 to 1.5, ethylenically unsaturated        double bonds per molecule, as described in DE 38 07 571 A1 on        pages 5 to 7, in DE 37 06 095 A1 in columns 3 to 7, in EP 0 358        153 B1 on pages 3 to 6, in U.S. Pat. No. 4,754,014 A in columns        5 to 9, in DE 44 21 823 A1 or in the international patent        application WO 92/22615 on page 12 line 18 to page 18 line 10,        or acryloxysilane-containing vinyl monomers, preparable by        reacting hydroxy-functional silanes with epichlorohydrin and        subsequently reacting that reaction product with (meth)acrylic        acid and/or hydroxyalkyl esters of (meth)acrylic acid.

>From these suitable monomers (a9) described by way of example above,the skilled worker is readily able to select those which areparticularly suitable for the respective end use, on the basis of theirknown physicochemical properties and reactivities. If appropriate, he orshe may carry out a few preliminary rangefinding experiments for thispurpose. In particular, he or she will ensure that the monomers (a9) donot contain any functional groups, especially (potentially) cationic oranionic functional groups, which enter into unwanted interactions withthe (potentially) anionic or cationic functional groups in thepolyurethanes (A).

In accordance with the invention, the monomers (a9) are selected suchthat the profile of properties of the grafted-on (co)polymers isdetermined essentially by the above-described (meth)acrylate monomers(a9), the other monomers (a9) broadly varying this profile of propertiesin an advantageous manner.

In accordance with the invention, very particular advantages result ifmixtures of the monomers (a91), (a92) and (a93) and also, if desired,(a96) are used.

Viewed in terms of its method, the preparation of the polyurethane(meth)acrylate graft copolymers (A) has no special features but insteadtakes place in accordance with the customary and known methods offree-radical (co)polymerization in bulk, solution or emulsion in thepresence of at least one polymerization initiator.

Where the (co)polymerization takes place in bulk or solution, thepolyurethane (meth)acrylate graft copolymer (A) is dispersed in anaqueous medium, so giving a secondary dispersion.

Preferably, the (co)polymerization is conducted in emulsion, asdescribed, for example, in patent DE 197 22 862 C1 or patentapplications DE 196 45 761 A1, EP-A 522 419 A1 or EP 0 522 420 A1, or inminiemulsion or microemulsion. For further details of miniemulsion andmicroemulsion, refer to patent applications and literature references DE196 28 142 A1, DE 196 28 143 A1 or EP 0 401 565 A1, EmulsionPolymerization and Emulsion Polymers, editors P. A. Lovell and MohamedS. El-Aasser, John Wiley and Sons, Chichester, N.Y., Weinheim, 1997,pages 700 et seq; Mohamed S. El-Aasser, Advances in EmulsionPolymerization and Latex Technology, 30th Annual Short Course, Volume 3,Jun. 7-11, 1999, Emulsion Polymers Institute, Lehigh University,Bethlehem, Pa., U.S.A. In the case of (co)polymerization in emulsion,miniemulsion or microemulsion, the graft copolymers of the invention areobtained in the form of primary dispersions.

Suitable reactors for the (co)polymerization processes are the customaryand known stirred vessels, cascades of stirred vessels, tube reactors,loop reactors or Taylor reactors, as described, for example, in patentsDE 1 071 241 A1, EP 0 498 583 A1, and DE 198 28 742 A1, and in thearticle by K. Kataoka in Chemical Engineering Science, Volume 50, No. 9,1995, pages 1409 to 1416.

The (co)polymerization is advantageously conducted at temperatures aboveroom temperature and below the lowest decomposition temperature of theparticular monomers used, the chosen temperature range being preferablyfrom 30 to 180° C., with very particular preference from 70 to 150° C.,and in particular from 80 to 110° C.

When using particularly volatile monomers (a9) and/or emulsions, the(co)polymerization may also be conducted under pressure, preferablyunder from 1.5 to 3000 bar, with particular preference from 5 to 1500bar, and in particular from 10 to 1000 bar.

Examples of suitable polymerization initiators are initiators which formfree radicals, such as dialkyl peroxides, for instance, di-tert-butylperoxide or dicumyl peroxide; hydroperoxides, such as cumenehydroperoxide or tert-butyl hydroperoxide; peresters, such as tert-butylperbenzoate, tert-butyl perpivalate, tert-butylper-3,5,5-trimethylhexanoate or tert-butyl per-2-ethylhexanoate;potassium, sodium or ammonium peroxodisulfate; azo dinitriles such asazobis-isobutyronitrile; C—C-cleaving initiators such as benzpinacolsilyl ethers; or a combination of a nonoxidizing initiator with hydrogenperoxide. It is preferred to use water-insoluble initiators. Theinitiators are used preferably in an amount of from 0.1 to 25% byweight, with particular preference from 2 to 10% by weight, based on theoverall weight of the monomers (a9).

In the polyurethane (meth)acrylate graft copolymers (A), the proportionof polyurethane (A) to grafted-on monomers (a9) may vary widely, whichis a particular advantage of the polyurethane (meth)acrylate graftcopolymers (A). Preferably, this ratio is from 1:100 to 100:1, morepreferably from 1:50 to 50:1, with particular preference from 30:1 to1:30, with very particular preference from 20:1 to 1:20, and inparticular from 10:1 to 1:10. Very particular advantages result if thisratio is approximately 3.5:1 to 1:3.5, in particular from 1.5:1 to1:1.5.

The amount of the polyurethanes (A) and/or of the polyurethane(meth)acrylate graft copolymers (A) to be used in accordance with theinvention as a proportion of the coating materials of the invention mayvary widely and is guided primarily by the intended use of the coatingmaterials, by the curing mechanism and by the functionality of thebinders (A) with respect to the crosslinking reaction with thecrosslinking agents that may be present. In accordance with theinvention it is of advantage to use the binders (A) in an amount of from5 to 70, preferably from 6 to 65, with particular preference from 7 to60, and in particular from 8 to 55% by weight, based in each case on thesolids of the coating material of the invention.

Preferably, the binders (A) are employed in the form of their aqueousdispersions for the preparation of the coating material of theinvention.

The further essential constituent of the coating material of theinvention is at least one color and/or effect pigment (B).

The pigments (B) may comprise both organic and inorganic compounds. Thecoating material of the invention, especially the aqueous basecoat andsolid-color topcoat of the invention, specifically the aqueous basecoatof the invention, therefore ensures, on the basis of this large numberof suitable pigments (B), a universal scope of use, and permits therealization of a large number of color shades and optical and otherphysical effects.

The effect pigments (B) are preferably selected from the groupconsisting of organic and inorganic, colored and achromatic,optical-effect, electrically conductive, magnetically shielding, andfluorescent pigments.

Examples of suitable optical-effect pigments (B) are metal flakepigments, such as standard commercial aluminum bronzes, aluminum bronzeschromated in accordance with DE 36 36 183 A1, standard commercialstainless steel bronzes, and nonmetallic effect pigments, such aspearlescent pigments and dichroic interference pigments, platelet-shapedeffect pigments based on iron oxide with a color from pink to brownishred, or liquid-crystalline effect pigments. For further details, referto Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, 1998, page176, “Effect pigments” and pages 380 and 381 “Metal oxide-mica pigments”to “Metal pigments”, and to patents and patent applications DE 36 36 156A1, DE 37 18 446 A1, DE 37 19 804 A1, DE 39 30 601 A1, EP 0 068 311 A1,EP 0 264 843 A1, EP 0 265 820 A1, EP 0 283 852 A1, EP 0 293 746 A1, EP 0417 567 A1, U.S. Pat. Nos. 4,828,826 A and 5,244,649 A and also Europeanpatents EP 0 736 076 B1, EP 0 736 077 B1 and EP 0 736 073 B1. It is alsopossible to use combinations of different effect pigments.

Examples of fluorescent pigments (B) (daylight-fluorescent pigments) arebis(azomethine) pigments.

Examples of suitable electrically conductive pigments (B) are titaniumdioxide/tin oxide pigments.

Examples of magnetically shielding pigments (B) are pigments based oniron oxides or chromium dioxide.

Color pigments (B) which can be used include organic and inorganicpigments.

Examples of suitable inorganic color pigments are white pigments, suchas titanium dioxide, zinc white, zinc sulfide or lithopones; blackpigments such as carbon black, iron manganese black or spinel black;chromatic pigments such as chromium oxide, chromium oxide hydrate green,cobalt green or ultramarine green, cobalt blue, ultramarine blue ormanganese blue, ultramarine violet or cobalt violet and manganeseviolet, red iron oxide, cadmium sulfoselenide, molybdate red orultramarine red; brown iron oxide, mixed brown, spinel phases andcorundum phases or chrome orange; or yellow iron oxide, nickel titaniumyellow, chrome titanium yellow, cadmium sulfide, cadmium zinc sulfide,chrome yellow or bismuth vanadate.

Examples of suitable organic color pigments are monoazo pigments, disazopigments, anthraquinone pigments, benzimidazole pigments, quinacridonepigments, quinophthalone pigments, diketopyrrolopyrrole pigments,dioxazine pigments, indanthrone pigments, isoindoline pigments,isoindolinone pigments, azomethine pigments, thioindigo pigments, metalcomplex pigments, perinone pigments, perylene pigments, phthalocyaninepigments or aniline black.

For further details, refer to Römpp Lexikon Lacke und Druckfarben, GeorgThieme Verlag, 1998, pages 180 and 181, “Iron blue pigments” to “Blackiron oxide”, pages 451 to 453, “Pigments” to “Pigment volumeconcentration”, page 563, “Thioindigo pigments”, page 567 “Titaniumdioxide pigments”, pages 400 and 467, “Naturally occurring pigments”,page 459, “Polycyclic pigments”, page 52, “Azomethine pigments”, “Azopigments” and page 379, “Metal complex pigments”.

Furthermore, it is possible as well to use pigments (B) which areselected from the group of extending, rheology control, scratchproofing,transparent or hiding and corrosion-protective pigments, such as metalpowders, organic and inorganic, transparent or hiding fillers ornanoparticles.

Examples of suitable metal powders (B) are powders of metals and metalalloys, such as aluminum, zinc, copper, bronze or brass.

An example of a corrosion-protective pigment (B) is zinc phosphate.

Examples of suitable organic and inorganic fillers (B) are chalk,calcium sulfates, barium sulfate, silicates such as talc, mica orkaolin, silicas, oxides such as aluminum hydroxide or magnesiumhydroxide, or organic fillers such as polymer powders, especially ofpolyamide or polyacrylonitrile. For further details refer to RömppLexikon Lacke und Druckfarben, Georg Thieme Verlag, 1998, pages 250 ff.“Fillers”.

It is preferred to employ mica and talc if the intention is to improvethe scratch resistance of the color and/or effect coats produced fromthe basecoat materials.

It is further advantageous to use mixtures of platelet-shaped inorganicfillers (B), such as talc or mica, and non-platelet-shaped inorganicfillers, such as chalk, dolomite, calcium sulfate or barium sulfate,since this allows the viscosity and rheology to be adjusted veryeffectively.

Examples of suitable transparent fillers (B) are those based on silica,alumina or zirconium oxide.

Suitable nanoparticles (B) are selected from the group consisting ofhydrophilic and hydrophobic, especially hydrophilic, nanoparticles basedon silica, alumina, zinc oxide, zirconium oxide and the polyacids andheteropolyacids of transition metals, preferably of molybdenum andtungsten, having a primary particle size <50 nm, preferably 5 to 50 nm,in particular 10 to 30 nm. The hydrophilic nanoparticles preferably haveno flatting effect. Particular preference is given to usingnanoparticles based on silica.

Very particular preference is given to using hydrophilic pyrogenicsilicas whose agglomerates and aggregates have a chainlike structure andwhich can be prepared by the flame hydrolysis of silicon tetrachloridein an oxyhydrogen flame. These are sold, for example, by Degussa underthe brand name Aerosil®. Very particular preference is also given tousing precipitated waterglasses, such as nanohectorites, which are sold,for example, by Südchemie under the brand name Optigel® or by Laporteunder the brand name Laponite®. Further examples of nanoparticles (B)are known from German patent applications

-   -   DE 195 40 623 A1, column 4 line 31 to column 5 line 30,    -   DE 197 19 948 A1, page 2 lines 42 to 67,    -   DE 197 46 885 A1, page 2 lines 42 to 68, or    -   WO 00/22052, page 5 line 9 to page 6 line 2.        The surface of the nanoparticles may have been modified. For        this purpose it is possible to use organic silicon compounds.

The pigment concentration of the coating material of the invention mayvary very widely and is guided primarily by the effect that is to bebrought about and/or by the opacity of the color pigments. The pigmentconcentration is preferably, in total, 3 to 90% by weight, based on thesolids of the coating material of the invention.

As a further inventively essential constituent, the coating material ofthe invention comprises at least one, especially one, dispersingassistant for the color and/or effect pigments (B), selected from thegroup consisting of the reaction products of

-   (c1) at least one, especially one, functionalized copolymer    containing    -   (c11) at least one, especially one, copolymerized olefinically        unsaturated monomer selected from the group consisting of        olefinically unsaturated monomers containing at least one        reactive functional group selected from the group consisting of        isocyanate groups, anhydride groups and epoxy groups; and    -   (c12) at least one, especially one, copolymerized olefinically        unsaturated monomer which is free from isocyanate-, anhydride-        and epoxy-reactive functional groups;-   (c2) at least one, especially one, homopolymeric polyalkylene    glycol, and-   (c3) at least one, especially one, compound of the general formula    I:    NR₂—C(O)—NR₂  (I)    -   in which the variables R are selected from the group consisting        of hydrogen atoms and saturated and unsaturated, substituted and        unsubstituted, aliphatic, cycloaliphatic,        aliphatic-cycloaliphatic, aromatic, aliphatic-aromatic and        cycloaliphatic-aromatic radicals which may contain at least one        amino group —NH—, at least one oxygen atom —O— and/or at least        one sulfur atom —S— and/or may be cyclically linked to one        another, at least one organic radical R being present and the        radical R or at least one of the radicals R containing at least        one reactive functional group selected from the group consisting        of isocyanate-, anhydride- and epoxy-reactive groups.

Examples of suitable olefinically unsaturated monomers (c11) and theamounts in which they are preferably employed are known from Europeanpatent application EP 0 589 340 A1, page 3 lines 35 to 54.

Examples of suitable olefinically unsaturated monomers (c12) and theamounts in which they are preferably employed are known from Europeanpatent application EP 0 589 340 A1, page 3 line 54 to page 4 line 6.

In addition it is possible to use functional, aromatic, olefinicallyunsaturated monomers (c13), especially the above-described aromaticolefinically unsaturated monomers (a96) and/or the aromatic olefinicallyunsaturated monomers known from European patent application EP 0 589 340A1, page 4 lines 7 to 15.

The copolymers (c1) are preferably prepared as described in Europeanpatent application EP 0 589 340 A1, page 5 line 31 to page 6 line 2, andhave the properties described therein.

Examples of suitable homopolymeric polyalkylene glycols (c2) are thepolyalkylene glycols described above in connection with the polyols (a2)and those described in European patent application EP 0 589 340 A1, page4 lines 17 to 28.

Examples of suitable compounds of the general formula I and the amountsin which they are preferably employed are known from European patentapplication EP 0 589 340 A1, page 4 line 39 to page 5 line 16.

The dispersing assistants (C) are preferably prepared by the processesdescribed in European patent application EP 0 589 340 A1, page 3 line 30to page 6 line 31 and page 7 line 32 to page 9 line 2. They preferablyhave a number-average molecular weight of from 3000 to 25 000, inparticular from 5000 to 12 000 daltons.

The amount of the dispersing assistant (C) in the coating material ofthe invention may vary very widely and is guided by the requirements ofthe case in hand, in particular by the dispersibility of the pigments(B). The dispersing assistants (C) are preferably employed in an amountof from 0.01 to 10%, more preferably from 0.02 to 5%, and in particularfrom 0.02 to 2% by weight, based in each case on the solids of thecoating material of the invention. The dispersing assistants (C) areincorporated into the coating material of the invention with particularpreference by way of the pigment formulations (cf. Römpp Online, GeorgThieme Verlag, Stuttgart, New York, 2002, “Pigment formulations”) orpigment pastes.

The coating material of the invention comprises not least at least onerheological aid (D) based on (meth)acrylate copolymers. Examples ofsuitable rheological aids (D) are described in Römpp Lexikon Lacke undDruckfarben, Georg Thieme Verlag, Stuttgart, New York, 1998,“Thickeners”, pages 599 to 600, and “Polyacrylic acids”, page 457, inGerman patent applications DE 196 52 842 A1 and DE 197 41 554 A1, and inthe textbook “Lackadditive” [Additives for coatings] by Johan Bieleman,Wiley-VCH, Weinheim, N.Y., 1998, pages 31 to 34. Preference is given tousing salts of polyacrylic acid. The rheological aids (D) are commercialproducts and are sold, for example, under the brand name Viscalex® HV30by Allied Colloids. In the coating material of the invention they areused in the customary and known amounts.

The coating material of the invention may further comprise at least onecrosslinking agent.

Examples of suitable crosslinking agents are amino resins, as described,for example, in Römpp Lexikon Lacke und Druckfarben, Georg ThiemeVerlag, 1998, page 29, “amino resins”, in the textbook “Lackadditive”[Additives for coatings] by Johan Bieleman, Wiley-VCH, Weinheim, N.Y.,1998, pages 242 ff., in the book “Paints, Coatings and Solvents”,second, completely revised edition, Eds. D Stoye and W. Freitag,Wiley-VCH, Weinheim, N.Y., 1998, pages 80 ff., in U.S. Pat. No.4,710,542 A1 and EP 0 245 700 A1, and in the article by B. Singh andcoworkers, “Carbamylmethylated Melamines, Novel Crosslinkers for theCoatings Industry”, in Advanced Organic Coatings Science and TechnologySeries, 1991, volume 13, pages 193 to 207; carboxyl-containing compoundsor resins, as described for example in patent DE 196 52 813 A1;compounds or resins containing epoxide groups, as described for examplein patents EP 0 299 420 A1, DE 22 14 650 B1, DE 27 49 576 B1, U.S. Pat.Nos. 4,091,048 A1 and 3,781,379 A1; blocked and unblockedpolyisocyanates, as described for example in U.S. Pat. No. 4,444,954 A1,DE 196 17 086 A1, DE 196 31 269 A1, EP 0 004 571 A1 and EP 0 582 051 A1,or described above as compounds (a1); and/ortris(alkoxycarbonylamino)triazines, as described in U.S. Pat. Nos.4,939,213 A1, 5,084,541 A1, 5,288,865 A1 and EP 0 604 922 A1.

The amount of the crosslinking agents in the coating material of theinvention may vary very widely and is guided in particular by theirfunctionality on the one hand and by the functionality of thepolyurethanes (A) on the other.

The coating material of the invention may further comprise at least oneorganic solvent (cosolvent). The cosolvent is preferably miscible withwater. Examples of customary and known cosolvents are described in D.Stoye and W. Freitag (eds.), “Paints, Coatings and Solvents”, 2nd,Completely Revised Edition, Wiley-VCH, Weinheim, N.Y., 1998, “14.9.Solvent Groups”, pages 327 to 373. In the coating material of theinvention they are used preferably in an amount of from 1 to 20%, inparticular from 2 to 18%, by weight based on the coating material of theinvention.

The coating material of the invention may further comprise at least oneneutralizing agent. Examples of suitable neutralizing agents are thosedescribed above in connection with the polyurethanes (A).

It is preferred to set a degree of neutralization of from 50 to 150 mol%, based on the potentially ionic groups present in the polyurethane(A).

The coating material of the invention may comprise not least at leastone typical coatings additive, selected from the group consisting oforganic and inorganic additives.

Examples of suitable typical coatings additives are additional binderscurable thermally and/or with actinic radiation, reactive diluents forthe thermal curing or actinic radiation curing, UV absorbers, lightstabilizers, free-radical scavengers, free-radical polymerizationinitiators, thermal crosslinking catalysts, photoinitiators andphotocoinitiators, slip additives, polymerization inhibitors, defoamers,emulsifiers, wetting agents, dispersants, adhesion promoters, levelingagents, film-forming auxiliaries, additional rheology control additives(thickeners) with the exception of phyllosilicates, flame retardants,siccatives, dryers, antiskinning agents, corrosion inhibitors, waxes,and flatting agents, as known, for example, from the textbook“Lackadditive” by Johan Bieleman, Wiley-VCH, Weinheim, N.Y., 1998.

The amount of the above-described additives in the coating material ofthe invention may vary very widely and is guided in particular by thefunction of the particular additive used. They are used advantageouslyin the amounts indicated in the prior art cited above.

The above-described essential constituents (A) to (D) and also the otherconstituents of the coating material of the invention that are presentwhere appropriate are in dispersion and/or solution in water. The solidscontent of the coating material of the invention may vary widely. It isguided in particular by the viscosity necessary for storage, transit,and application. This should on the one hand prevent the settling of theconstituents on storage and in transit. On the other hand it shouldensure trouble-free application with effective flow of the resultingpaint films. It is preferred to employ a solids content of from 10 to60%, more preferably 12 to 58%, with particular preference 14 to 56%,and in particular 16 to 54% by weight, based in each case on the coatingmaterial of the invention.

The coating material of the invention may be prepared by all customaryand known processes for preparing aqueous basecoat materials. Thedispersions may be sheared using a customary and known mixing apparatussuch as a stirred vessel, a homogenizer, a dissolver, a stirred mill, aSupraton or an Ultraturrax. It is a particular advantage of the processof the invention that the pseudoplasticity is built up relativelyrapidly even in a comparatively weak shear field as provided by a simplestirrer. There is therefore no need for expensive andmaintenance-intensive apparatus necessary for generating strong shearfields. Surprisingly, skinning is avoided as well.

The coating material of the invention, especially the aqueous basecoatof the invention, is outstandingly suited to the production of multicoatcolor and/or effect paint systems on primed and unprimed substrates bythe wet-on-wet method. Furthermore, the coating material of theinvention, especially the solid-color topcoat material of the invention,is outstandingly suited to producing single-coat color and/or effectpaint systems.

The coating material of the invention exhibits particular advantages inits use as an aqueous basecoat as part of the wet-on-wet method, inwhich the aqueous basecoat material is applied to the primed or unprimedsubstrate, after which the aqueous basecoat film is dried, but notcured, a clearcoat material is applied to the aqueous basecoat film, andthe resulting clearcoat film is cured thermally, or thermally and withactinic radiation (dual cure), together with the aqueous basecoat film.

In the case of a primed substrate, the primer, especially the surfacerfilm, may be overcoated in the uncured or only part-cured state with theaqueous basecoat material of the invention and with the clearcoatmaterial, after which all three films are baked together.

In another variant of the wet-on-wet method, a first aqueous basecoatfilm is applied to an uncured or only part-cured primer, especially anelectrodeposition coating film, that is present on the substrate, andthen the two films are thermally cured together. The resultant coatingis then overcoated as described above with a second aqueous basecoat andclearcoat. In this case, the first or the second aqueous basecoat may beproduced from an aqueous basecoat material of the invention.Alternatively, both aqueous basecoats may be produced from a singleaqueous basecoat material of the invention, or from two materiallydifferent aqueous basecoat materials of the invention.

Suitable coating substrates are all surfaces which are not damaged bycuring of the films present thereon with the use of heat or with thecombined use of heat and actinic radiation (dual cure). Suitablesubstrates comprise, for example, metals, plastics, wood, ceramic,stone, textile, fiber composites, leather, glass, glass fibers, glasswool, rockwool, mineral- and resin-bound building materials, such asplasterboards, cement slabs or roof shingles, and assemblies of thesematerials.

The coating materials of the invention are therefore outstandinglysuitable for producing decorative, functional and/or protective coatingson motor vehicle bodies and parts thereof, the interior and exterior ofmotor vehicles, interior and exterior architecture, doors, windows,furniture and hollow glassware and also in the context of the industrialcoating of small parts, coils, containers, packaging, electricalcomponents and white goods.

In the case of electrically conductive substrates it is possible to useprimers prepared in customary and known manner from electrodepositioncoating materials. Suitable for this purpose are both anodic andcathodic electrodeposition coating materials, but especially cathodic.Usually, especially in automotive finishing, a surfacer coating orantistonechip primer is applied subsequently, which is regarded as partof the primer. Electrodeposition coating materials and surfacers mayalso be applied wet-on-wet and subjected to joint thermal curing.

It is also possible to use primed or unprimed plastics parts, providedthey are dimensionally stable under the thermal curing conditionsemployed. In the case of unfunctionalized and/or nonpolar substratesurfaces, these may be subjected conventionally to a pre-coatingpretreatment, such as with a plasma or by flaming, or may be providedwith a hydroprimer.

The coating materials of the invention may be applied by any of thecustomary methods, such as spraying, knife coating, brushing, flowcoating, dipping, impregnating, trickling or rolling, for example. Thesubstrate to be coated may itself be at rest, with the applicationequipment or unit being moved. Alternatively, the substrate to becoated, especially a coil, may be moved, with the application unit beingat rest relative to the substrate or being moved appropriately. Wherethe coating materials of the invention include constituents which can beactivated with actinic radiation, application is conducted preferably inthe absence of actinic radiation.

In general, the electrodeposition coating film, surfacer film,solid-color topcoat film of the invention, aqueous basecoat film of theinvention and clearcoat film are applied in a wet-film thickness suchthat their curing results in coatings having the coat thicknessesadvantageous and necessary for their functions.

In the case of the electrodeposition coat, this coat thickness is from10 to 100, preferably from 10 to 80, with particular preference from 10to 60, and in particular from 10 to 40 μm.

In the case of the surfacer coat, it is from 10 to 150, preferably from10 to 120, with particular preference from 10 to 100, and in particularfrom 10 to 90 μm.

In the case of the solid-color topcoats of the invention, it is from 10to 100, preferably from 10 to 80, with particular preference from 10 to60, and in particular from 10 to 40 μm.

In the case of the aqueous basecoat of the invention, it is from 5 to50, preferably from 5 to 40, with particular preference from 5 to 30,and in particular from 10 to 25 μm.

In the case of the clearcoats, it is from 10 to 100, preferably from 15to 80, with particular preference from 20 to 70, and in particular from25 to 60 μm.

Alternatively, it is possible to employ the multicoat system known fromEuropean patent application EP 0 817 614 A1, comprising anelectrodeposition coat, a first basecoat, a second basecoat, and aclearcoat, in which the total coat thickness of the first and secondbasecoats is from 15 to 40 μm and the coat thickness of the firstbasecoat is from 20 to 50% of said overall coat thickness.

The coating films of the invention are preferably cured thermally, orthermally and with actinic radiation (dual cure).

Curing may take place after a certain resting time. This may have aduration of from 30 s to 2 h, preferably from 1 min to 1 h, and inparticular from 1 min to 45 min. The resting time is used, for example,for the leveling and degassing of the coating films or for theevaporation of volatile constituents such as solvent. The resting timemay be assisted and/or shortened by the application of elevatedtemperatures of up to 90° C. and/or by a reduced atmospheric humidity<10 g water/kg air, especially <5 g/kg air, provided that this does notentail any damage or change to the coating films, such as prematurecomplete crosslinking, for instance.

In the case of two-component or multicomponent systems of the invention,curing actually begins under the conditions indicated above.

The thermal curing has no special features as to its method but insteadtakes place in accordance with the customary and known methods, such asheating in a convection oven or irradiation with IR lamps. The thermalcuring may also take place in stages.

Preferably, the thermal crosslinking of the one-component systems of theinvention is conducted at temperatures above 100° C. In general it isadvisable not to exceed temperatures of 180° C. here, preferably 160° C.and in particular 155° C.

Preferably, curing with actinic radiation is carried out with UVradiation and/or electron beams. Preference is given in this case toemploying a dose of from 1000 to 3000, preferably from 1100 to 2900,with particular preference from 1200 to 2800, with very particularpreference from 1300 to 2700, and in particular from 1400 to 2600mJ/cm². If desired, this curing may be supplemented by actinic radiationfrom other radiation sources. In the case of electron beams, it ispreferred to operate under an inert gas atmosphere. This can be ensured,for example, by supplying carbon dioxide and/or nitrogen directly to thesurface of the coating films. In the case of UV radiation curing, aswell, it is possible to operate under inert gas or an oxygen-depletedatmosphere in order to prevent the formation of ozone.

Curing with actinic radiation is carried out using the customary andknown radiation sources and optical auxiliary measures. Examples ofsuitable radiation sources are flashlamps from the company VISIT, high-or low-pressure mercury vapor lamps, with or without lead doping inorder to open up a radiation window of up to 405 nm, or electron beamsources. Their arrangement is known in principle and may be adapted tothe circumstances of the workpiece and of the process parameters. In thecase of workpieces of complex shape, as envisaged for automobile bodies,the regions not accessible to direct radiation (shadow regions) such ascavities, folds and other structural undercuts, may be (partially) curedusing pointwise, small-area or all-round emitters in conjunction with anautomatic movement apparatus for the irradiation of cavities or edges.

The equipment and conditions of these curing methods are described, forexample, in R. Holmes, U.V. and E.B. Curing Formulations for PrintingInks, Coatings and Paints, SITA Technology, Academic Press, London,United Kingdom 1984.

This curing may be carried out in stages, i.e., by multiple exposure orirradiation with actinic radiation. It may also take place inalternation, i.e., by curing alternately with UV radiation and electronbeams.

If thermal curing and actinic radiation curing are employed together,these methods may be used simultaneously or alternately. If the twocuring methods are used alternately, it is possible, for example, tocommence with thermal curing and to end with actinic radiation curing.In other cases it may prove advantageous to commence with actinicradiation curing and to end with it. Particular advantages result if thecoating films are cured in two separate steps, first with actinicradiation and then thermally.

In the context of the coating processes of the invention, theabove-described application and curing methods may also be employed forthe production of the surfacer coats and clearcoats.

In the case of repair to multicoat color and/or effect paint finishes itis possible to apply the coating materials of the invention withoutspecial pretreatment and/or auxiliary means to the surfaces that are tobe repaired.

The single-coat and multicoat paint systems of the invention haveoutstanding optical, mechanical, and chemical properties. They are freefrom wetting defects, runs, popping marks, pinholes, clouds, effectdefects, water spots, and shifts in shade. They also meet all therequirements imposed in terms of wet adhesion and stonechip resistancefollowing exposure to constant condensation conditions and followingexposure to boiling water and subsequent jetting with a high pressuresteam jet. In particular, with the multicoat finishes of the invention,no film delamination in the course of high-pressure cleaning with hotsteam is observed, owing to their outstanding wet adhesion properties.

Furthermore, the coatings of the invention offer further advantages.Thus they are an effective physical barrier to the diffusion ofplasticizers, adhesives, antioxidants or solvents, and are of high heatresistance. They have good antistatic properties and offer significantlyimproved corrosion protection and significantly improved wettingproperties.

Consequently, the substrates of the invention, especially bodies ofautomobiles and commercial vehicles, interior and exterior architecture,industrial components, including plastics parts, small parts, packaging,coils, white goods, and electrical components, or furniture, doors,windows, and hollow glassware, which are coated with at least onecoating of the invention exhibit particular technical and economicadvantages, in particular a long service life, so making themparticularly attractive to the users.

EXAMPLES Preparation Example 1

The Preparation of a Binder Dispersion (A)

The polyurethane (meth)acrylate graft copolymer (A) was prepared inaccordance with the instructions given in German patent application DE44 37 535 A1 on page 7 lines 36 to 53, “C Preparation of an acrylatedpolyurethane dispersion”.

For this purpose, a polyester diol was prepared first of all from 29.41parts by weight of neopentyl glycol, 16.7 parts by weight of1,6-hexanediol and 44.2 parts by weight of adipic acid in 8.8 parts byweight of methyl isobutyl ketone and also 0.86 part by weight ofcyclohexane as entrainer.

In analogy to the instructions indicated above, a polyurethane wasprepared from 1.87 parts by weight of neopentyl glycol, 17.4 parts byweight of the polyester diol solution, 0.6 part by weight oftrimethylolpropane monoallyl ether and 12.82 parts by weight ofisophorone diisocyanate in the presence of 0.010 part by weight ofdibutyltin dilaurate and also 20.527 parts by weight of methyl isobutylketone, and was chain-extended with 3.056 parts by weight oftrimethylolpropane.

The resultant polyurethane solution was used as the initial charge forthe copolymerization of a monomer mixture of 14.041 parts by weight ofn-butyl acrylate, 14.04 parts by weight of methyl methacrylate, 3.36parts by weight of hydroxypropyl methacrylate and 2.62 parts by weightof acrylic acid. The initiator solution used was a mixture of 6.72 partsby weight of methyl isobutyl ketone and 1.02 parts by weight oftert-butyl peroxy-2-ethylhexanoate.

Dimethylethanolamine in 47.05 parts by weight of water was added to51.84 parts by weight of the resultant acrylated polyurethane solution,after which the methyl isobutyl ketone was removed by distillation. Theresultant acrylated polyurethane dispersion had a solids content of 44%by weight.

Preparation Example 2

The Preparation of a Dispersing Assistant (C)

The dispersing assistant (C) was prepared in accordance with theinstructions specified in European patent application EP 0 589 340 A1,page 7 lines 33 to 45, “Example 1, Preparation of Isocyanate FunctionalAcrylic Copolymer 1” and page 8 lines 28 to 42, “Example 5, Preparationof Modified Copolymer (Grind Resin) 1”.

Preparation Example 3

Preparation of a Pigment Paste

A pigment paste was prepared by mixing 7.5 parts by weight of dispersingassistant (C) from preparation example 2, 6 parts by weight of thebinder dispersion (A) from preparation example 1, 35 parts by weight ofa standard commercial green pigment, 0.3 part by weight of ligroin, 1.3parts by weight of methyl isoamyl ketone, 0.1 part by weight ofdimethylethanolamine, 3.5 parts by weight of Pluriol® P 900(poly(oxypropylene) glycol from BASF Aktiengesellschaft), 44 parts byweight of deionized water and 6 parts by weight of 1-propoxy-2-propanol,and milling the resulting mixture.

Example 1

The Preparation of an Aqueous Basecoat Material of the Invention

The aqueous basecoat material of the invention was prepared by mixing4.56 parts by weight of Cymel® 327 (90% in isobutanol), 2.88 parts byweight of Cymel® 303 (both melamine-formaldehyde resins from CytecSpecialty Resins A.S.), 1.46 parts by weight of Pluriol® P 900(poly(oxypropylene) glycol from BASF Aktiengesellschaft), 2.47 parts byweight of butyl glycol, 2.23 parts by weight of butyl diglycol, 3.35parts by weight of Shellsol® T, 1.75 parts by weight of Solventnaphtha®,1.32 parts by weight of N-methylpyrrolidone, 0.66 part by weight ofwetting agent solution (tetramethyldecynediol, 52% by weight in butylglycol), 0.8 part by weight of leveling additive solution, Agitan® 281(standard commercial additive, 100%), 0.92 part by weight of a standardcommercial blocked sulfonic acid (Nacure® 2500 from King Industries, 25%in isopropanol), 9.67 parts by weight of Aerosil paste (6% by weight ofAerosil R 972/431 in water, from Degussa), 9.6 parts by weight of thebinder dispersion (A) of preparation example 1, 31 parts by weight ofthe pigment paste of preparation example 3, 18 parts by weight ofViscalex® HV30 from Allied Colloids, and 2.5 parts by weight of aneutralizing agent solution (dimethylethanolamine, 10% in water) in astirred vessel with one another.

The green aqueous basecoat material of the invention was completelystable on storage at room temperature at 40° C. At these temperatures itcould be sheared without problems without any settling of constituentsor phase separation. The required pseudoplasticity was built up bysimple stirring. No skinning was observed.

Example 2

The Production of a Color Multicoat Paint System of the Invention

To produce the color multicoat paint system of example 2 the aqueousbasecoat material of example 1 was used.

To test the shift in shade the aqueous basecoat material was processed,in a first series, immediately following its preparation. The multicoatpaint system in question formed the standard against which the othermulticoat paint systems of the second and third series were compared. Inthe case of the second series the aqueous basecoat materials were storedat 40° C. for seven days (temperature exposure). In the case of thethird series they were stirred at low shear forces for two weeks(shearing load).

The color shades of the multicoat paint systems were measured by theCIELAB method, using an X-Rite colorimeter. Standardized illuminantswere used. The differences from the standard were then calculated. Theresults can be found in the table.

Additionally, in order to test the wetting properties, the aqueousbasecoat materials were applied in wedge form to glass plates and testpanels with baked surfacer coatings.

To test the adhesion properties and mechanical stability of the aqueousbasecoats, test panels measuring 10×20 cm were produced conventionally.This was done by coating steel panels (bodywork panels) coated with aconventional cathodically deposited and baked electrocoat (EC) with astandard commercial low-build surfacer (Ecoprime® 60 from BASF CoatingsAG), after which the resulting surfacer film was flashed off at 20° C.and a relative humidity of 65% for five minutes and dried in a forcedair oven at 80° C. for five minutes. The surfacer coat thereafter had adry film thickness of 15 μm.

After the test panels had been cooled to 20° C. the unexposed aqueousbasecoat material was applied, flashed off at 20° C. and a relativehumidity of 65% for five minutes and dried in a forced air oven at 80°C. for five minutes, so that the dried aqueous basecoat films had a dryfilm thickness of approximately 15 μm.

After the test panels had again been cooled to 20° C. the aqueousbasecoat films were overcoated with a powder slurry clearcoat materialas per international patent application WO 96/32452. The resultantpowder slurry clearcoat films were flashed off at 20° C. and a relativehumidity of 65% for 3 minutes and dried in a forced air oven at 55° C.for 5 minutes. The dry film thickness of the resultant clearcoats was 55to 57 μm.

Following the application of all three coats they were baked together at135° C. for 30 minutes to give the multicoat paint system of theinvention.

The test panels in question are referred to below as “original panels”.Prior to testing and the application of the refinishes, they were storedin a controlled-climate chamber at 23° C. and a relative humidity of 50%for 24 hours.

To test the clearcoat wetting, test panels were produced in the mannerdescribed above, with the clearcoat material being applied in wedgeform.

Some of the original panels were provided with a refinish in accordancewith ISO 1520. These panels are referred to below as “refinish panels”.

The original panels and the refinish panels were subjected to thecross-cut test of DIN ISO 2409: 1994-10.

Additionally, the original panels and the refinish panels weresubjected, following exposure under constant condensation conditions(CCC), to the NedCar stonechip test VCKN4441. This stonechip test, itsevaluation, and the rating of the results are common knowledge in theart.

Not least, the adhesion properties of the color multicoat paint systemson the original panels and refinish panels were tested after the panelshad been exposed to boiling water by means of the high pressure test.Following exposure, a cross was inscribed in each of the multicoat paintsystems. The scribed areas were sprayed with a water jet (Walterinstrument type LTA2; pressure: 80 bar; water temperature: 80° C.;nozzle tip/test panel distance: 12 cm; exposure period: 30 seconds;apparatus setting: F2). The degree of spalling was assessed visually andrated as follows:

Rating Degree of spalling 0 none 1 slight 2 slight to moderate 3moderate 4 severe 5 complete

The results of these tests can be found in the table. They underscorethe fact that the aqueous basecoat material of the invention fromexample 1 and the multicoat paint systems of the invention from example2 (original panels and refinish panels) exhibited outstanding clearcoatwetting, wetting of glass, wetting of surfacer coats, adhesive strength,mechanical stability, and shade stability.

TABLE Performance properties of the multicoat paint system of theinvention Test method and treatment Example 2 Wetting properties:Clearcoat wetting: from 4-5 μm Wetting of glass: very good Wetting ofsurfacer coat: very good Cross-cut on: Original panels GT0 Refinishpanels GT0 NedCar VCKN 4441 stonechip test: Before exposure to CCCOriginal panels: 10 Refinish panels: 8A After exposure to CCC: Originalpanels: 8A Refinish panels 7A High pressure test: Original panels: 0Refinish panels: 0 Shade stability: After 40° C. storage Delta in E/D 65light 1.98 Delta in E/A light 1.97 Delta in E/B light 2 After stirringtest: Delta in E/D 65 light 0.75 Delta in E/A light 0.75 Delta in E/Blight 0.76

1. An aqueous color, effect, or color and effect coating material whichis free from rheological aids based on phyllosilicates, comprising: (A)at least one polyurethane which is water-soluble, water-dilutable;water-dispersible, of a combination thereof, selected from the groupconsisting of ionically stabilized polyurethanes based onpolyisocyanates; ionically and nonionically stabilized polyurethanesbased on polyisocyanates; ionically stabilized polyurethanes based onpolyisocyanates and grafted with olefinically unsaturated compounds; andionically and nonionically stabilized polyurethanes based onpolyisocyanates and grafted with olefinically unsaturated compounds;wherein the polyisocyanates are selected from the group consisting ofaliphatic polyisocyanates, cycloaliphatic polyisocyanates,aliphatic-cycloaliphatic polyisocyanates, aromatic polyisocyanates,aliphatic-aromatic polyisocyanates, cycloaliphatic-aromaticpolyisocyanates, and a combination thereof; (B) at least one colorpigment, effect pigment, or color and effect pigment; (C) at least onedispersing assistant for the color pigment, effect pigment, or color andeffect pigments, comprising the reaction products of: (c1) at least onefunctionalized copolymer comprising: (c11) at least one copolymerizedolefinically unsaturated monomer comprising at least one reactivefunctional group selected from the group consisting of isocyanategroups, anhydride groups and epoxy groups; and (c12) at least onecopolymerized olefinically unsaturated monomer which is free fromisocyanate-, anhydride- and epoxy-reactive functional groups; (c2) atleast one homopolymeric polyalkylene glycol, and (c3) at least onecompound of the general formula I:NR₂—C(O)NR₂  (I) in which the variables R are selected from the groupconsisting of hydrogen atoms and organic, saturated and unsaturated,substituted and unsubstituted, aliphatic, cycloaliphatic,aliphatic-cycloaliphatic, aromatic, aliphatic-aromatic andcycloaliphatic-aromatic radicals which may contain at least one aminogroup —NH—, at least one oxygen atom —O—and/or at least one sulfur atom—S—and/or may be cyclically linked to one another, at least one organicradical R being present and the radical R or at least one of theradicals R containing at least one reactive functional group selectedfrom the group consisting of isocyanate-, anhydride- and epoxy-reactivegroups; and (D) at least one rheological aid based on (meth)acrylatecopolymers.
 2. The coating material of claim 1, curable thermally orthermally and with actinic radiation.
 3. The coating material of claim1, which is selected from the group consisting of a one-componentsystem, a two-component system, and a multicomponent system.
 4. Thecoating material of claim 1, wherein the at least one effect pigment (B)is selected from the group consisting of organic and inorganic, coloredand achromatic, optical-effect, electrically conductive, magneticallyshielding, and fluorescent pigments and mixtures thereof.
 5. The coatingmaterial of claim 1, wherein the at least one color pigments (B) isselected from the group consisting of organic and inorganic pigments. 6.The coating material of claim 1, further comprising pigments (B)selected from the group consisting of extending, rheology control,scratchproofing, corrosion-protective, transparent, and hiding pigmentsand mixtures thereof.
 7. The coating material of claim 1, wherein the atleast one rheological aid (D) comprises salts of polyacrylic acid. 8.The coating material of claim 1, further comprising at least onecrosslinking agent, at least one organic solvent, at least oneneutralizing agent, and at least one organic or inorganic coatingsadditive.
 9. The coating material of claim 8, wherein the at least oneorganic or inorganic coatings additive is selected from the groupconsisting of non-(A) binders curable thermally and/or with actinicradiation, reactive diluents for the thermal curing or actinic radiationcuring, UV absorbers, light stabilizers, free-radical scavengers,free-radical polymerization initiators, thermal crosslinking catalysts,photoinitiators and photocoinitiators, slip additives, polymerizationinhibitors, defoamers, emulsifiers, wetting agents, dispersants,adhesion promoters, leveling agents, film-forming auxiliaries, non-(D)rheology control additives (thickeners) with the exception ofphyllosilicates, flame retardants, siccatives, dryers, antiskinningagents, corrosion inhibitors, waxes, and flatting agents and mixturesthereof.
 10. A single-coat color and/or effect paint system comprisingthe coating material of in claim
 1. 11. A substrate comprising thesingle-coat color and/or effect paint system of claim 10, selected fromthe group consisting of motor vehicle bodies and parts thereof, theinterior and exterior of motor vehicles, interior and exteriorarchitecture, doors, windows, furniture, hollow glassware, small parts,coils, containers, packaging, electrical components, and white goods andcombinations thereof
 12. A multicoat color and/or effect paint systemcomprising the coating material of in claim
 1. 13. A substratecomprising the multicoat color and/or effect paint system of claim 12,selected from the group consisting of motor vehicle bodies and partsthereof, the interior and exterior of motor vehicles, interior andexterior architecture, doors, windows, furniture, hollow glassware,small parts, coils, containers, packaging, electrical components, andwhite goods and combinations thereof.